[TYPO3] Can't log to the install tool

[Fred]

I have installed Typo3 v4.1 on my server :

- windows 2000
- IIS et framework .net
- PHP 4.3.6
- MySQL 4.0.18

I changed my password for the install tool, I'm logged out but I can't log-in.
If I put the wrong password I have the log-in box and the md5() hash value, but when It's the good one I simply have the log-in box again and again.
I tried to install the quickstart 3.8.1 and the problem is the same.

Does anyone have a clue or can tell me if it's possible to disable the password ?